Conventional lawnmowers typically employ one of the three methods to process the clippings. The first method is to discharge the clippings onto the lawn using a discharging mower. This permits nutrients to return to the soil. However, in most cases, discharging mowers expel the clippings on top of the grass along a row (called “windrow”). Because the clippings are left on top of the grass, the clippings will not efficiently decompose and return nutrients to the soil. These windrows can mar the aesthetics of a freshly manicured lawn. If the windrows are heavy, then they can even cause the grass over which they lie to turn brown, further detracting from the appearance and health of the lawn.
The second method of processing the clippings includes discharging the clippings into a collection bag attached to a discharging mower. The collection bag is attached to the outlet of the mower's discharge chute. Bagging the clippings prevents the formation of windrows on the lawn. However, the lawnmower operator must make frequent stops to empty the bag. Disposing the bagged clippings places an additional burden on the operator.
These first two methods can create additional maintenance requirements for the lawnmower when cutting heavy and/or wet vegetation. The clippings can collect in the deck housing and randomly drop on the lawn in large clumps. The clippings can also collect in the discharge chute and ultimately block the discharge chute. The operator must then stop the lawnmower and clean out the discharge chute.
The third method offers solutions to the disadvantageous first and second methods. In the third method, the clippings are cut into fine pieces using a mulching mower so that they are much smaller than those produced by discharge mowers using either of the other two methods. A mulching mower provides several advantages over discharging mowers. For example, the clippings are small enough to be blown below the surface of the lawn. This enables the elimination of the discharge chute, thus simplifying the design and manufacture of the lawnmower and reducing the operator's maintenance activities while mowing. Mulching also minimizes the effect of the clippings on the aesthetics of the lawn because the grass is deposited on the lawn across a significantly wider area. This at least minimizes the windrow effect. The mulching process forces the clippings below the top of the grass so that the rate of re-absorption of nutrients into the soil increases as compared to a regular discharging mower that merely deposits the clippings on top of the grass. U.S. Pat. No. 5,210,998 discloses a typical mulching mower and is incorporated into this application by reference.
Mulching mowers suffer from a problem in which the clippings hover above the cutting blade, circulate inside the deck housing and collect on the deck housing. This can cause the deck housing to become clogged and distribute the clippings unevenly onto the lawn.
Recent attempts to solve this problem resulted in obstructions mounted in the deck housing to redirect the circulation path of the clippings back toward the blade for mulching and depositing in the lawn. Typically, these obstructions involve complicated shapes and require specific positioning within the deck housing to ensure proper performance.